Elucidating the synergy of layer-by-layer TMDC-TMN deposition for superior electrochemical performance in supercapattery devices

Supercapatteric devices can combine the advantages of batteries and supercapacitors, addressing their individual limitations in power and energy density. This study focuses on enhancing the electrochemical performance of battery-grade electrodes through the strategic incorporation of transition metal dichalcogenides and transition metal nitrides, specifically tungsten disulfide. Utilizing the magnetron sputtering, we integrated conductive layers of chromium nitride and titanium nitride between substrate and WS₂. Results of thorough electrochemical testing revealed that the initial specific capacity (Q_s) of WS₂ was 600 C/g. However, by incorporating interfacial layers of CrN and TiN, the Q_s was significantly improved 830 C/g and 1230 C/g, demonstrating the substantial impact of interface engineering on overall performance of WS₂. The fabricated supercapatteric devices, demonstrated exceptional performance, with WS₂/CrN//AC achieving Q_s of 950 C/g and WS₂/TiN//AC reaching a Q_s of 1100 C/g. Moreover, WS₂/CrN//AC and WS₂/TiN//AC attained power densities of 6800 W/kg (with 99.8 % capacity retention) and 7108 W/kg (with 99.9 % capacity retention), respectively, and energy densities of 98 Wh/kg and 135 Wh/kg, highlighting the superior performance and stability of WS₂/TiN//AC. Additionally, for examining the diffusive and capacitive behaviors of devices, two different semi-empirical models were further used and compared. This work emphasizes the potential of interface engineering in enhancing the performance of hybrid energy storage (HES) systems.